LOCATION LOFFTUS OR+NVEstablished Series
TAXONOMIC CLASS: Ashy, glassy, mesic Aquicambidic Haplodurids
TYPICAL PEDON: Lofftus ashy silt loam--rangeland. (Colors are for dry soil unless otherwise noted.)
Akn--0 to 2 inches; gray (10YR 6/1) ashy silt loam, dark grayish brown (10YR 4/2) moist; moderate very thin platy structure; slightly hard, friable, very sticky and moderately plastic; many very fine and fine roots; common fine vesicular pores; strongly effervescent, carbonates are disseminated; white salt and black organic staining occur in patches on the soil surface; very strongly alkaline (pH 9.6); clear smooth boundary. (2 to 8 inches thick)
Bkn1--2 to 12 inches; light gray (10YR 7/1) ashy silt loam, dark grayish brown (2.5Y 4/2) moist; weak very thin platy structure; slightly hard, friable, very sticky and moderately plastic; many very fine and fine roots; common very fine tubular pores; strongly effervescent, carbonates are disseminated; strongly alkaline (pH 8.8); clear smooth boundary. (9 to 15 inches thick)
Bkn2--12 to 30 inches; light gray (10YR 7/1) ashy silt loam, dark grayish brown (2.5Y 4/2) moist; weak very thin platy structure; soft, very friable, very sticky and moderately plastic; many fine and medium roots to 24 inches, few below; violently effervescent, carbonates are disseminated; strongly alkaline (pH 8.8); abrupt smooth boundary. (9 to 20 inches thick)
2Bkqm--30 to 50 inches; light gray (10YR 7/1) cemented material, dark grayish brown (2.5Y 4/2) moist; very hard, very firm, brittle; strongly cemented by silica; few fine tubular pores; silica coats lining some pores and on the upper surface of the horizon; violently effervescent; carbonates are disseminated; strongly alkaline (pH 8.8). (15 to 30 inches thick)
3C--50 to 60 inches; stratified silt loam to loamy fine sand.
TYPE LOCATION: Lake County, Oregon; about 10 miles southeast of Adel in Coleman Valley; near the center of the SE1/4 of the SE1/4 of section 7, T. 41 S., R. 25 E.
RANGE IN CHARACTERISTICS:
Soil moisture - The soils are dry for more than half the time when soil temperature is greater than 41 degrees F. The soil temperature is above 41 degrees F. from about March 15 to about November 15; Aridic moisture regime that borders on xeric.
Mean annual soil temperature - 47 to 51 degrees F.
Depth to strongly cemented duripan - 20 to 40 inches.
Depth to bedrock - Greater than 60 inches.
Volcanic glass content - 30 to 60 percent in coarse silt through fine sand fractions.
Bulk density - 0.80 to 1.00 g/cc.
Salinity (EC): 8 to 16 mmhos/cm.
Sodicity (SAR): 25 to 50.
Calcium carbonate equivalent - 2 to 8 percent.
Reaction - Strongly alkaline or very strongly alkaline.
Other features - Moist chroma of 2 or less in the matrix is inherited from the parent material and are not believed to be developed from saturation.
A horizon
Value: 6 or 7 dry, 3 or 4 moist.
Chroma: 1 or 2 moist.
Other features: An efflorescence of white salt and black to dark brown organic staining commonly occur on the soil surface.
Bkn horizons
Hue: 10YR, 2.5Y, or neutral (N).
Value: 6 or 7 dry, 4 or 5 moist.
Chroma: 0 through 2, dry or moist.
Other features: Layers of white volcanic ash a few inches thick are in some pedons.
2Bkqm horizon
Cementation: Strongly cemented.
3C horizon
Texture: Stratified silt loam to loamy fine sand.
COMPETING SERIES: There are currently no other series in this family.
GEOGRAPHIC SETTING: Lofftus soils are on basin-floor remnants. These soils formed in formed in lacustrine deposits and surficial deposits of eolian volcanic ash. Slopes are 0 to 1 percent. Elevations range from 4,000 to 4,800 feet. The climate is semiarid and characterized by cool, moist winters and warm, dry summers. The mean annual precipitation is 8 to 10 inches, the mean annual temperature is 47 to 50 degrees F., and the frost-free period is 90 to 110 days.
GEOGRAPHICALLY ASSOCIATED SOILS: These are the Helphenstein, Icene, Turpin, Mesman, and Reese soils. These soils do not have strongly cemented duripans between 20 to 40 inches.
DRAINAGE AND PERMEABILITY: Somewhat poorly drained; medium surface runoff; moderate permeability (moderately high or high saturated hydraulic conductivity). Endosaturation is present with a perched water table between 1 and 3 feet (shallow and moderately deep free water occurrence classes) between March and June. Cumulative annual duration class is Common.
USE AND VEGETATION: Lofftus soils are used for livestock grazing and wildlife habitat. The native vegetation is inland saltgrass, basin wildrye, and black greasewood.
DISTRIBUTION AND EXTENT: South-central Oregon and northwestern Nevada. These soils are not extensive with about 2,000 acres of the series mapped to date. MLRA 23.
MLRA OFFICE RESPONSIBLE: Reno, Nevada.
SERIES ESTABLISHED: Lake County, Oregon (Southern Part), 1991.
REMARKS: Diagnostic horizons and features recognized in this pedon are:
Ochric epipedon - The zone from the soil surface to 2 inches (Akn horizon).
Duripan- The zone from 30 to 50 inches (2Bkqm horizon).
Endosaturation feature - The condition of perched ground water between 12 and 36 inches at certain times during normal years (Bkn2 horizon).
Particle-size control section and ashy substitute class with glassy mineralogy - The zone from 10 to 30 inches (Bkn2 horizon and part of the Bkn1 horizon).
The taxonomic classification was changed from coarse-silty, mixed, mesic Haploxerollic Durorthids on 4/26/90.